This invention relates generally to gas turbine engines, and more particularly, to methods for replacing a portion of a combustor dome assembly.
A turbine engine includes a compressor for compressing air which is mixed with a fuel and channeled to a combustor wherein the mixture is ignited within a combustion chamber for generating hot combustion gases. At least some known combustors include a dome assembly, a cowling, and liners to channel the combustion gases to a turbine, which extracts energy from the combustion gases for powering the compressor, as well as producing useful work to propel an aircraft in flight or to power a load, such as an electrical generator. The liners are coupled to the dome assembly with the cowling, and extend downstream from the cowling to define the combustion chamber.
At least some known dome assemblies include a structural member (herein referred to as a dome plate) with a fuel and air swirl chamber that extends forward, or upstream, from the dome plate, and a thermal protection feature, (herein referred to as a deflector plate) that extends aftward, or downstream. The number of swirl chambers and deflector plates is variably selected depending upon the gas turbine engine application. The flame in a gas turbine is typically generated just downstream of the dome, where the fuel and air mixture is sufficient to maintain the combustion process. At least some known dome assemblies include multiple components that through a complex shape facilitate containing the flame released by the fuel-air mixture. Such components may, for example, consist of a single unit, or may be manufactured separately and assembled together to facilitate improved maintainability and repairability. More specifically, at least some known dome assemblies include deflector plates coupled to a downstream side of the dome plate to shield the structural dome plate from high temperatures generated within the combustor. Typically, the deflector plates are coupled within the dome assembly using either a welding process or a brazing process.
Over time, continued exposure to high temperatures may induce oxidation erosion or thermal fatigue cracking damage to the deflector plates. To facilitate effective shielding of the dome plate, damaged deflector plates may require replacement. At least some known repair methods include conventional machining the dome assembly to remove the damaged deflector plates. However, because of the relatively close location of the swirl chamber attachment feature, conventional machining techniques may not be possible without damaging or removing the swirl chamber. Furthermore, if the machining is successful, often times precise dimensional relations between the remaining combustor dome assembly components may be altered and as a result, special tooling may be required during reassembly. Thus, replacing a portion of a combustor dome assembly may be a time-consuming and expensive process.
In one aspect, a method for replacing a portion of combustor dome assembly is provided. The dome assembly includes at least one deflector plate and a dome cup including a swirl cup including an interface feature that defines a slot therein for locating a deflector plate. The deflector plate extends downstream from the dome plate and swirl cup such that a portion of the deflector plate is securely fixed within the interface feature. The method comprises cutting through an interface formed between the deflector assembly and the swirl cup slot, extending the cut substantially circumferentially between the deflector plate and the swirl cup slot through the at least one swirl cup, removing the deflector assembly from the combustor dome assembly, and coupling a replacement deflector plate from the existing swirl cup within the combustor dome assembly that extends aft from the portion of the combustor dome assembly that is upstream from the cut.
In another aspect of the invention, a method for replacing a portion of a combustor dome assembly within a gas turbine engine combustor is provided. The dome assembly is at an upstream end of a combustion chamber defined within the combustor, and includes at least one swirl cup including an interface feature and at least one deflector plate that extends aftward from the interface feature. The at least one deflector plate is coupled to the at least one swirl cup with at least one of a braze process and a weld process. The method comprises forming a substantially annular cut through the interface features formed by at least one of weld material and braze material, removing the deflector plate from the combustor, and coupling a replacement deflector plate into the combustor to extend downstream from the interface feature.
In a further aspect, a method for replacing a portion of a gas turbine engine combustor dome assembly is provided. The method comprises using an electro-discharge machining process to cut through an interface formed between a swirl cup and a deflector plate coupled therein, removing the deflector plate from the combustor, and coupling a replacement deflector plate into the existing swirler interface feature.